Tahmoh Penikett will help Criminal Minds celebrate a milestone.

The former Battlestar Galactica star, who played a key role early on Supernatural Season 9, will appear on the CBS drama's 200th episode, producer Rick Dunkle confirmed this week via the following Instagram photo:

According to TV Line, Penikett will portray Michael Hastings, an unwelcome  blast from JJ's past from her days at the DoD.

Look for the special episode to focus on JJ's time away from the BAU, answering questions raised this year by Esai Morales' Mateo Cruz.

Penikett has also appeared on Continuum, Castle and The CW’s upcoming Star-Crossed.

You can watch Criminal Minds online now in preparation for tonight's 199th installment, which airs at 9/8c on CBS.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.